Hmm. Although this is within the marks, you probably are pushing the envelope with that high a supply.

Moderate volume is probably not much power-wise, since you can produce 90dB with one watt on a moderate speaker. So it canīt be the power.

Those modules produce power for the controller directly from the rails with dropper resistors which inevitably dissipates power. This is probably what you encounter as standby loss. Some slightly more elaborate scheme (albeit inevitably more pricey...) would cater for this.

-h

I exchanged my Transformer with a 65V switching PSU board. The Bords are much cooler now. I haven't expected such an impact on the heat dissapation, cause the Board is rated up to 80V. Seems like the 80V is a limited time surival limit and the recommanded 70V shouldn't be exeeded.